Powering low end GPUs

[MeistroUK]

I've got a rig made with 1060/1070s but i was curious...

So what if it was say 6 x RX 560s that have no 6 pin power, would you be able to power 2 x risers from the SATA cable - so 3 separate cables from the PSU and it would get the rest of the power from the motherboard since there low powered cards?

[pickleburglar]

You have 2 bottlenecks, if both can handle it then yes, if not then no

1. The SATA power connector is designed for up to 4.5A (54W @ 12v)
2. The wire carrying the 2 sata connectors has to support the combined current. Read the gauge on the wire and consult this chart: https://www.powerstream.com/Wire_Size.htm

AWG 18 is very common in PSU's and is designed for up to 16A (192W @ 12v) but cheaper PSU's sometimes use AWG 20 which is 11A or even 22 which is only 7.

If you're using powered risers then the cards get no power from the motherboard, only though the riser.

Example 1: You have a good quality PSU with AWG16 wires and it has a cable that has 3xAMP connectors. The wire supports 22 amps and the connectors supports 13 amps so the maximum each connector can drain is 88W. PCIe standard specifies that a card should not drain more than 75w so you can easily hook up 3 cards to one cable!

Example 2: You have a crappy PSU with AWG20 wires and it has a cable with 2xSATA connectors. The wire supports 11amps and the connectors support 4.5 amps so the maximum each connector can rain is 54W. If you video cards drain less than 54W then you're ok. If more then you'll have some melted connectors.

[MeistroUK]

Ok... Well a Rosewill 650w Capstone G is a pretty decent PSU - it's AWG 18 i read on a review. Well then maybe 3 x risers that can take a 6 pin PCIe might be better and 3 x sata ones - connecting one cable to 2 x risers and the other cable to 1 x riser and the ssd.

Wish they just put power headers on them, would make things so much easier.

[pickleburglar]

I've never seen a riser that uses SATA connectors directly, all of them come with SATA->AMP adapter wire and your PSU has 4 AMP connectors anyways so you can just skip the adapter and use those. It has a higher amp rating and also, I really don't trust noname chinese power adapters. I've received some that say AWG18 on the wire but when one of them melted, I cut it open and it was actually AWG24, fire hazard..

[MeistroUK]

Yea that's what I'm using on my build just now, 6 x PCIe risers and plug the sata from the PSU directly in... When I'm looking just now though i see most off them now have sata to 6 pin though.

[chandrarahmadewa]

Yea that's what I'm using on my build just now, 6 x PCIe risers and plug the sata from the PSU directly in... When I'm looking just now though i see most off them now have sata to 6 pin though.

Maybe what you mean is ATA/Molex, I also never seen riser with SATA power. The old Riser using "SATA to MOLEX " power, and we can power it directly from PSU using Molex.

[pickleburglar]

Molex.

just nitpicking a little - molex is a general term for all the pin-socket connectors inside a computer, it is also the name of the company that first started making them. When people say molex connector they usually mean the AMP 1-480424-0 which oddly enough is one of the few connectors not invented or produced by molex

[whoismoses]

I have a 9 card RX550 Rig. I power each riser with a combination of PCI-e cables, molex cables and SATA. When it comes to SATA I only do one card per cable...

HOWEVER

I was curious. I powered all the cards with SATA.

I did 3 cards per SATA cable, seemed to work fine. I let it run for 2 days, no issues. I was using a EVGA 850w gold PSU.

I changed it back away from SATA only because I felt it was safer.